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Three genes have been identified that cause, in humans, autosomally inherited parkinsonism. These are PARK2, encoding the E3 ubiquitin ligase parkin; PINK1, a mitochondrial kinase; and PARK7, which codes for the protein DJ-1. In several experimental systems, it has been shown that all three proteins impact mitochondrial function and/or oxidative stress responses. These are probably related because mitochondria produce oxidative stress in neurons. Moreover, it is clear that there are relationships between these genes, with a single pathway linking PINK1 and parkin and a parallel relationship with DJ-1. Work in progress in the field is aimed at understanding these relationships in more depth.
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Mark Cookson (2012) studied this question.
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